Microspheres and microparticles, such as described in U.S. Pat. Nos. 5,344,452, and 7,442,389, the entire contents of which are incorporated herein by reference, made of for example polymethylmethacrylate (PMMA) or other materials, are currently combined with foreign carrier materials (e.g., gelatinous bovine collagen) and injected or introduced into the body to accomplish augmentation or repair of various tissues or anatomical structures. The gelatinous bovine collagen has been used as the carrier of choice due to its' many favorable attributes, including its' ability to hold the microspheres in suspension below certain temperatures, its' tissue healing and cell generation properties, and its' low immune response rate in humans
The use of largely denatured gelatinous bovine collagen as a carrier for such microspheres and microparticles has several major drawbacks. The melting point of the largely denatured gelatinous bovine collagen (the Tm for gelatinous 3.5% collagen is approximately 26.5° C.) is well below the normal body temperatures, and as such those microspheres and microparticles settle out of suspension when exposed to temperatures well below normal body temperatures and even at higher end room temperatures. The resorption rate of the gelatinous bovine collagen in the human body is also only a matter of a few days, which does not allow sufficient time for host tissue to completely replace the carrier material before it is absorbed into the body, removing the anchoring support structure around the microparticles before they can be supported by new host tissue. Additionally, the gelatinous bovine collagen carrier must be stored and handled quickly at refrigeration temperatures in order to maintain the microspheres in uniform suspension. It is also undesirable because the extrusion forces necessary to express the gelatinous bovine material from a syringe at those temperatures are excessive. In addition, the gelatinous bovine collagen and other gel carriers do not have sufficient shear resistance and resistance to deformation to adequately push the microspheres or microparticles into dense tissue while maintaining the necessary homogenous distribution.
There exists a need for enhanced carrier materials capable of providing properties that solve the issues stated above, so that microspheres and microparticles can be effectively delivered into patient tissues and anatomical structures for augmentation or repair.